How much force is needed to lift a 25-kg mass at a constant verlocity?

-- In order to achieve constant verlocity, the net force on the mass must be zero.  So if there ARE any forces acting on it, they must be balanced.

-- There is already a force on the mass that can't be eliminated . . . the force of gravity.

-- That force due to gravity is (mass x gravity) = (25 kg)(9.8 m/s²) = 245N in the downward direction.

-- In order to 'balance' the forces and make them add up to zero, we have to provide another force of 245N, all in the upward direction.

-- Then the forces on the object will be balanced, the NET force on it will be zero, and whichever way you start it moving, it will continue to move at a cornstant verlocity.

f = 245 N

Explanation:

see the solution

the second one and the forth one are in the purple because they are opinions and the rest are in the yellow

explanation:

96.77 amp

explanation:

rl = 250/100 = 2.5 ohms.

egl = 250 + (100 × 0.1) + 2 = 262 v.

at 700 r.p.m., eg2 = 262 × 700/1000 = 183.4 v.

if ia is the new current, then eg2 - 2 - (ia × 0.1) = 2.5 ia

which means this will give ia = 96.77 amp.